Hyperdry System (one-way purge valve) for easy clearing
The narrowest center joints eliminate the vision field split.
The M-21 is a stylish two-window mask featuring the Hyperdry system for easier mask clearance. The advanced design makes the purge valve almost invisible from the outside. The M-21 allows for easy replacement with corrective lenses. This mask is designed so air is discharged on the sides of the mask, thus maintaining the field of vision. The purge valve is on the bottom of the left lens. Just tilt your face slightly to the left and blow through your nose gently for smooth water discharge.